736 THE RESPIRATION AND [pt. iii 



pregnancy is entirely due to the embryo. This attitude is adopted 

 by Garipuy & Sendrail as the result of their work^. Sandiford & 

 Wheeler have made this point of view very much the most satis- 

 factory by calculating from their own figures and those of all other 

 observers the (basal) metabolic rate of the embryo on this assump- 

 tion. The weight of the foetus was obtained by means of the standard 

 curves for human pre-natal growth, and Lissauer's formula for in- 

 fants (10-3 x\W^ instead of Meeh's 12-3 x\/W^) was used to 

 calculate its surface at the different stages. Then the weight and 

 surface (Dubois charts) of the pregnant woman being known, and 

 the weight of the foetus subtracted from it, the metabolic rate of 

 the mother alone could be calculated. The result was that the sum 

 of the two agreed remarkably well with the figures actually found 

 experimentally. 



More explicitly what Sandiford & Wheeler did was this. Sandiford 

 had previously calculated the surface area of the human embryo at 

 different stages, and this value, added to the calculated surface area 

 of a woman equal in weight to the pregnant woman minus the 

 foetus, gave the total surface in question. Then, when the total 

 calories eliminated by mother and foetus were divided by the sum 

 of the surface areas so obtained, the resulting figures would repre- 

 sent the heat production of a unit mass of active protoplasmic tissue. 

 It was found that actually there was no significant change during 

 pregnancy in this value, which remained constant within small 

 limits of variation at 35 calories per square metre per hour. Sandi- 

 ford and Wheeler pointed out that this calculation would be invalid 

 if surface area law depended on Newton's Law of Cooling, but was 

 valid if it depended, as in their opinion and in that of Boothby & 

 Sandiford, it did, on a proportionality between surface area and 

 mass of active protoplasmic tissue. I shall again return to this point. 

 They also used another method of calculation. They assumed that 

 the heat-production per unit mass of foetal tissue was constant 

 throughout foetal life, and, by multiplying the heat-production for 

 each square metre of body-surface each hour by the surface area of 

 the foetus corresponding to its estimated weight, the total calories 

 each hour for the foetus were obtained for the various months. If 

 this latter figure was subtracted from the total calories of mother 

 and foetus, the total calories of the mother alone were obtained, 



^ See also Pommrenke, Haney & Meek. 



